Philippine officials accused China on Wednesday of expanding reclamation work in disputed waters of the South China Sea, as the United States again called for restraint in the territorial conflict.

Philippine and US officials spoke as the longstanding allies ended a two-day strategic dialogue in Manila, reaffirming defence and economic cooperation.

"The Chinese activities in the West Philippine Sea (South China Sea) continue to be a serious concern, arising from reports of greater development in reclamation," Philippine defence undersecretary Pio Lorenzo Batino told reporters.

Batino refused to elaborate on the progress of the reclamation, saying only: "It's very serious. It has grown."

Philippine foreign undersecretary Evan Garcia described the Chinese reclamation work as "massive" and a violation of an agreement among South China Sea claimants not to build new structures until a binding code of conduct is in place.

"It is not helpful in finding a way forward. It is not an example of what everyone would understand as self-restraint," Garcia said.

China's claim to much of the South China Sea conflicts with claims by the Philippines as well as those of Brunei, Malaysia, Taiwan and Vietnam (AFP Photo/)

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